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flink1.10 异常 this type (GenericType<pojo) cannot be used as key.

实现功能： 统计单词个数

代码如下：

public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setParallelism(1);
        String path = "D:\\cjj\\test.txt";
        DataStream<String> ds = env.readTextFile(path);
        SingleOutputStreamOperator<WordCountModel> maps = ds.flatMap(new FlatMapFunction<String, WordCountModel>() {
            @Override
            public void flatMap(String s, Collector<WordCountModel> out) throws Exception {
                String[] words = s.split("\\s");
                for (String word : words) {
                    out.collect(WordCountModel.of(word.trim(), 1l));
                }
            }
        });
        maps.keyBy("word").sum("num").print();
        env.execute("提交任务");
    }

实体类：

public class WordCountModel {
    private String word;
    private Long num;
    private Integer age;

    public static WordCountModel of(String word, Long num) {
        WordCountModel wordCount = new WordCountModel();
        wordCount.word = word;
        wordCount.num = num;
        wordCount.age = 12;
        return wordCount;
    }

    @Override
    public String toString() {
        return word + " " + num;
    }
}

当我们用java pojo类进行分组聚合计算时汇报如下错误信息：


org.apache.flink.api.common.InvalidProgramException:

This type (GenericType) cannot be used as key.

出现这种情况解决办法:

1、实体类所有变量都是public

2、keyby用到的变量不能是布尔类型的

3、添加无参构造函数（flink1.10不需要）

修改后的实体类

public class WordCountModel {
    public String word;
    public Long num;
    public Integer age;

    public static WordCountModel of(String word, Long num) {
        WordCountModel wordCount = new WordCountModel();
        wordCount.word = word;
        wordCount.num = num;
        wordCount.age = 12;
        return wordCount;
    }

    @Override
    public String toString() {
        return word + " " + num;
    }
}

运行结果:

注意：实体类没有参与运算的属性也必须是public